E-cigarettes may lead to nicotine addiction

E-cigarettes appear to be a new route to nicotine addiction and heavier use of conventional cigarettes, a UCSF study in South Korea has found.

E-cigarettes appear to be a new route to nicotine addiction and heavier use of conventional cigarettes, a UCSF study in South Korea has found.

Photo: Yana Paskova, New York Times

E-cigarettes may lead to nicotine addiction

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E-CIGARETTES

Device may lead to nicotine addiction

E-cigarettes are promoted as safe alternates to cigarettes, but may only serve as a new route to nicotine addiction among adolescents, a new UCSF study has found.

E-cigarettes are battery-powered devices that look like cigarettes and deliver nicotine and other chemicals. Researchers assessed their use among youth in South Korea, where the devices are marketed similarly to how they are marketed in the United States.

In the analysis, researchers found that 4 out of 5 South Korean adolescents who use e-cigarettes also smoke tobacco cigarettes. Young e-cigarette smokers, they added, are more likely to have tried to quit smoking, which suggests they think e-cigarettes will help wean them from smoking.

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In fact, the researchers found, the use of e-cigarettes was associated with heavier use of conventional cigarettes. And that means, they concluded, that the nicotine in e-cigarettes is addictive.

E-cigarette use has increased considerably in South Korea. Less than 1 percent of youths tried the product in 2008, when it was introduced, but more than 9 percent reported using it in 2011. In the U.S., about 1.78 million U.S. students reported using e-cigarettes as of 2012, according to the Centers for Disease Control and Prevention.

The study appeared last week in the Journal of Adolescent Health.

- Stephanie M. Lee

ATRIAL FIBRILLATION

Heart monitor predicts risk well

A commonly used heart monitor may accurately predict a person's risk of the most frequently diagnosed type of irregular heart rhythm, known as atrial fibrillation, according to a new study from UCSF and other institutions.

The Holter monitor is a portable electronic device used to monitor the electrical activity of a person's heart.

Monitoring patients with a 24-hour Holter monitor, researchers found that a subject's risk for atrial fibrillation later in life was substantially higher when they had more premature atrial contractions, also known as premature heartbeats.

Atrial fibrillation occurs when rapid, random electrical signals cause the two upper chambers of the heart, the atria, to contract irregularly and quickly, and patients with it may not show any symptoms.

From 1989 to 1990, researchers studied a random sample of people 65 years and older who underwent 24-hour Holter monitoring as part of a national study. The Holter showed that of the 1,260 participants, those without previously diagnosed atrial fibrillation had an 18 percent increased risk for the disorder if diagnosed with the premature heartbeats.

The study was published this week in the Annals of Internal Medicine.

- Stephanie M. Lee

BRAIN

Scientists probe astrocytes' role in pruning neurons

Stanford scientists have shown that star-shaped brain cells called astrocytes play a critical role in "pruning" the communication pathways between neurons, a process that makes the brain highly adaptable during early development years.

Astrocytes make up roughly a third of the cells in the brain, but until recently, scientists had little understanding about their purpose other than to support the neurons that let us see, hear, move and create memories.

The new research, done in mice, showed that astrocytes use two key proteins to engulf and destroy synapses that are no longer needed.

Scientists increasingly have been looking at astrocytes and other brain cells to determine whether it's possible to preserve some of the brain plasticity that marks early development and makes it so easy for young minds to adapt and learn.

They're also hunting for ways in which synaptic pruning can go wrong, and how cells like astrocytes could be harnessed to keep the pruning process in check.

The Stanford research was published online Nov. 24 in the journal Nature.

- Erin Allday

MALARIA

Mosquito interbreeding a concern

Two types of mosquitoes that are notorious spreaders of malaria appear to crossbreed far more often than scientists thought, a finding that could be important in developing tools to attack the insects, according to researchers from UC Davis.

There are multiple subgroups of the African malaria mosquito, called Anopheles gambiae. Two of those subgroups, known as M and S forms, were thought to rarely breed outside their own group.

But a 21-year study of mating habits in one village in Mali revealed that from 5 to 97 percent of new insects were hybrids. Previously, scientists had thought hybrids made up less than 1 percent. The UC Davis team found great variance, too - in one year, the rate of crossbreeding jumped from zero to 12 percent.

The question remains just how much genetic material the two subgroups share. Scientists worry, for example, whether one subgroup might pass on a genetic resistance to certain insecticides.

Results of their work were published Nov. 19 online in the Proceedings of the National Academy of Sciences.

- Erin Allday

CORNEAL TRANSPLANT

Age of donor and success rate

In almost all cases, the age of the donor makes little difference in the success of a corneal transplant, according to scientists with UC Davis Health System's Eye Center.

When the corneal tissue comes from people between ages 34 and 71 - who make up three quarters of corneal donors - the chance of the transplant lasting at least 10 years is 75 percent.

The success rate improves dramatically when the corneas come from very young donors - about 96 percent when the donor is age 12 to 33 - and it falls to 62 percent when the donor is older than 71.

But many surgeons won't use tissue from donors older than 65, or sometimes even 50. The UC Davis research suggests that practice may be too conservative, especially since there are not enough corneal donations to treat everyone who needs them worldwide.

Corneal transplants are a common sight-preserving surgery; more than 45,000 procedures were done in the United States in 2012.

The UC Davis research was published online Nov. 15 in the journal Ophthalmology.